docs: def utcoffset(self, dt, is_dst=None):
          '''See datetime.tzinfo.utcoffset
  
          The is_dst parameter may be used to remove ambiguity during DST
          transitions.
  
          >>> from pytz import timezone
          >>> tz = timezone('America/St_Johns')
          >>> ambiguous = datetime(2009, 10, 31, 23, 30)
  
          >>> tz.utcoffset(ambiguous, is_dst=False)
          datetime.timedelta(-1, 73800)
  
          >>> tz.utcoffset(ambiguous, is_dst=True)
          datetime.timedelta(-1, 77400)
  
          >>> try:
          ...     tz.utcoffset(ambiguous)
          ... except AmbiguousTimeError:
          ...     print('Ambiguous')
          Ambiguous
  
          '''
          if dt is None:
              return None
          elif dt.tzinfo is not self:
              dt = self.localize(dt, is_dst)
              return dt.tzinfo._utcoffset
          else:
              return self._utcoffset